Abstract
PURPOSE: The aim of this study was to examine the risk factors of infrapatellar fat pad (IFP) fibrosis and the associations between the degree of IFP fibrosis and clinical outcomes in patients who underwent anterior cruciate ligament reconstruction (ACLR). METHODS: A total of 97 patients who underwent primary ACLR using autologous hamstring tendons were divided into the mild fibrosis group (M group) and severe fibrosis group (S group), based on IFP fibrosis scoring (Grades 0-5) on magnetic resonance imaging at 3 months postoperatively. Clinical outcomes at 1 year postoperatively were compared between groups. Univariate logistic regression analysis was performed to determine factors associated with IFP fibrosis. Additionally, multiple linear regression analysis was performed to investigate whether IFP fibrosis affected clinical outcomes at 1 year postoperatively. RESULTS: Patients were classified into the S group (n = 21) and the M group (n = 76). There were significantly more males (p = 0.036), higher body mass index (p = 0.004), longer operation times (p = 0.031), and more cartilage injuries identified during arthroscopy (p = 0.030) in the S than M group. International Knee Documentation Committee (IKDC) subjective scores (p = 0.040), and Knee Injury and Osteoarthritis Outcome Score (KOOS) symptoms (p = 0.009) and quality of life values (p = 0.026) were significantly lower in the S than M group. The range of motion was significantly worse on both extension (p < 0.001) and flexion (p = 0.002) in the S than M group. Multiple regression analysis revealed IFP fibrosis as an independent factor affecting the IKDC subjective score (p = 0.037), KOOS-symptom subscore (p = 0.037) and extension angle (p = 0.002). CONCLUSIONS: Male sex, high BMI, prolonged surgery, and articular cartilage damage are risk factors for IFP fibrosis after ACLR. IFP fibrosis affects the range of motion and subjective patient evaluations at 1 year postoperatively. MRI-based evaluation at 3 months may help identify high-risk patients, and early interventions targeting fibrosis could improve postoperative recovery. LEVEL OF EVIDENCE: Level III, case-control study.